title: Two-photon solvatochromism II: experimental and theoretical study of solvent effects on the two-photon absorption spectrum of Reichardt's dye.
abstract: In this study, we report on the influence of solvent on the two-photon absorption (2PA) spectra of Reichardt's dye (RD). The measurement of 2PA cross-sections is performed for three solvents (chloroform, dimethyl formamide, and dimethyl sulfoxide) using the Z-scan technique. The key finding of this study is the observation that the cross-section, corresponding to the 2PA of the intramolecular charge-transfer state, diminishes substantially upon increasing the solvent polarity. To unravel the solvent dependence of the 2PA cross-section, the electronic structure of RD is determined using a hybrid quantum mechanics/molecular mechanics (QM/MM) approach, in which polarization between the solute and solvent is taken into account by using a self-consistent scheme in the solvent polarization. The two-state approximation proves to be adequate for the studied system, and allowed the observed solvent-polarity-induced decrease of the 2PA cross-section to be related to the decrease of the transition moment and the increase in the excitation energy.
authors.affiliation: Theoretical Chemistry Group, Institute of Physical and Theoretical Chemistry, Wrocław University of Technology, Wyb. Wyspiańskiego 27, 50370 Wrocław (Poland).
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Wielgus
authors.forename: Robert
authors.initials: R
authors.lastname: Zaleśny
authors.forename: N Arul
authors.initials: NA
authors.lastname: Murugan
authors.forename: Jacob
authors.initials: J
authors.lastname: Kongsted
authors.forename: Hans
authors.initials: H
authors.lastname: Ågren
authors.forename: Marek
authors.initials: M
authors.lastname: Samoc
authors.forename: Wojciech
authors.initials: W
authors.lastname: Bartkowiak
mesh_terms: D008958:Models, Molecular; D017785:Photons; D011726:Pyridinium Compounds / Q000737:chemistry*; D011789:Quantum Theory; D012997:Solvents / Q000737:chemistry
chemical_list: C541029:2,6-diphenyl-4-(2,4,6-triphenyl-1-pyridinio)phenolate; D011726:Pyridinium Compounds; D012997:Solvents
keywords: absorption; charge transfer; density functional calculations; solvatochromism; solvent effects